Pump element for a tube pump

ABSTRACT

The invention relates to a tube pump comprising a tube and a pump element inserted in the tube, where the pump element comprises a rod element and a first and a second non-return valve member positioned a distance apart on the rod element. The valve members are oriented in the same direction relative to the rod element so as to allow for a fluid flow in the tube through the first valve member, along the rod element, and through the second valve member. The tube comprises an at least partly flexible tube portion between the valve members such that a repeated deformation of the flexible tube portion acts to alternately close and open the valve members thereby generating a fluid flow through the tube. The invention further relates to a pump element comprising at least two non-return valve members connected by a rod element, and for insertion in an at least partly flexible tube in such tube pump as mentioned above, thereby acting to generate a fluid flow through the tube upon repeated deformation of the tube between the two valve members. The pump element may comprise a connecting part for coupling to another tube and may comprise a sealing part establishing a fluid tight connection to a part of the tube. The invention further relates to a method for creating a flow of a fluid within an at least partly flexible tube by means of a pump element as mentioned above.

FIELD OF THE INVENTION

The present invention relates to a tube pump comprising a pump elementinserted in a tube for the generation of a fluid flow within the tube.The invention furthermore relates to a pump element for such a tube pumpand to a method of creating a flow of a fluid within an at least partlyflexible tube.

BACKGROUND

Different kinds of positive displacement tube pumps such as roller pumpsor peristaltic pumps are known for pumping a fluid through a flexibletube or hose and are widely used in e.g. medical applications such asfor instance in infusion pump systems, dialysis pumps, or bypass pumpsfor circulatory support.

A benefit of such pump types making them especially advantageous inmedical applications is the absence of moving parts in contact with thefluid, whereby the pumps may be relatively easily sterilized. Theperistaltic pumps, roller pumps and tube pumps however suffer from anumber of drawbacks. Firstly, the pumping involves a complete or nearcomplete compression or squeezing of the tube either by rollers, contactplates, or shoes to obtain the desired fluid flow within the tube. Thisinevitably leads to large wear on the part of the tube within the pump.The tube therefore regularly needs to be moved relative to the pump forthe compression to be exerted on another part of the tube or exchangedcompletely thereby resulting in an excessive use of tube material and aneed for longer tubes. The extra tube length or the moving of thepressure zones makes the known tube pumps more expensive and increasesthe time needed to setup and operate the pump. Further, the large wearincreases the risk of damaging the hose considerably, leading to a lossof pumping fluid and contamination of the surroundings, and a reductionor loss of pumping effect which depending on the circumstances may beunacceptable and even fatal. Extra surveillance of the pump and tubes istherefore required to prevent such situations.

Further, the complete or near complete compression of the tube or hosemay result in excessive large stresses and shear forces experienced bythe fluid causing damages to the fluid molecules or separation ofcolloids and slurry fluids.

Another drawback of the known tube pumps is their often considerablesize necessitating a large amount of space which in many medicalsituations is limited.

DESCRIPTION OF THE INVENTION

It is therefore an object of embodiments of the present invention toovercome or at least reduce some or all of the above describeddisadvantages of the known tube and peristaltic pumps by providing atube pump and a pump element with improved pumping efficiency andreduced wear of the tube material. It is a further object of embodimentsof the invention to provide pump elements and tube pumps with minimizedrisk of leakages.

It is a further object of embodiments of the invention to provide pumpelements for tube pumps which are simple and fast to apply and yeteffective. It is a yet further object of embodiments of the invention toprovide products of minimal number of parts and of low manufacturingcosts.

In accordance with the invention this is obtained by a tube pumpcomprising a tube and a pump element inserted in the tube, the pumpelement comprising a rod element and at least a first and a secondnon-return valve member positioned a distance apart on the rod elementand oriented in the same direction relative to the rod element so as toallow for a fluid flow in the tube through the first valve member, alongthe rod element, and through the second valve member. The tube comprisesan at least partly flexible tube portion between the first and secondvalve members such that a repeated deformation of the flexible tubeportion acts to alternately close and open the valve members therebygenerating a fluid flow through the tube.

The non-return valve may be a so-called check valve, a clack valve, orone-way valve, and is a mechanical device, a valve, which normally willallow a fluid (liquid or gas) to flow through it in only one direction.The non-return valve may close the fluid passageway off partly or fullyin its closed position. By orienting the non-return valve members in thesame direction relative to the rod element is obtained that both valvemembers when in their open position will allow for a fluid flow in thetube in the same direction.

The whole tube may be flexible and may be made in a material such as athermoplastic or a rubber, and may be reinforced. Alternatively oradditionally, only a portion of the tube may be flexible, such ascomprising a length of a flexible hose or comprising flexible tube wallportions.

By a tube pump according to the above may by very simple means beobtained an effective pump for and mechanism for pumping a fluid throughthe tube. The fluid flow is generated as the deformation of the tubebetween the at least two non-return valve members acts to squeeze thefluid out of the tube space between the valve members and out throughone of the non-return valve members. When the deformation is relaxed, anegative pressure is created in the space, closing the one valve memberand opening the other drawing in fluid from upstream the tube. Arepeated deformation repeats the above described alternately opening andclosing of the valve members thereby generating a fluid flow within thetube.

The deformation may in an embodiment of the invention involve acompression of the tube from one or more sides and/or may involve adecompression of the tube.

Unlike many conventional tube pumps such as roller pumps, the tube neednot be completely compressed or squeezed to generate an efficientpumping motion of the fluid. Rather, even relatively small deformationsof the tube may be enough to obtain a relatively high pumping efficiencydue to the construction of the tube pump with the pump elementcomprising two or more non-return valve members. This is furtheradvantageous in minimizing the wear on the tube caused by the repeatingdeformation and thereby minimizing the risk of leaking and loss of thefluid and contamination of the surroundings.

The smaller amount of deformation of the tube needed for obtaining anefficient pump further leads to lower stresses and shear forcesexperienced by fluid, which may prevent damaging of fluid molecules andhelp to keep colloids and slurry fluids from separating. This may beespecially advantageous in pumping of specific types of fluid such ase.g. blood or other fluids comprising fragile or vulnerable components.

Due to the construction of the pump element of the valve memberspositioned on a rod element, a tube may fast and easily made ready forpumping by simply inserting a pump element into the tube. Similarly, thepump element may be extracted from the tube in an equally simplefashion, whereby the interior of the tube which then is the only part ofthe pump in contact with the fluid is left without obstacles and may becleaned and sterilized easily and effectively. The extracted pumpelement is likewise simple to clean and sterilize effectively beforereuse or may simply be disposed of. This makes the tube pump especiallyadvantageous for medical applications and in the food industry.

The tube pump is further advantageous in that it may be operated todeliver a pulsed flow e.g. like the heart which may be advantageous ine.g. bypass pumps or in some infusion pumps.

The pump element may be pre-manufactured in one or more sizesdimensioned to tubes of different diameters and/or shapes.

The tube pump is advantageous in comprising only few parts and can befast and easily assembled and made ready for pumping. Further, the tubepump is inexpensive to manufacture and inexpensive to maintain as theuse of a hose or tube makes for a relatively low-cost maintenance itemcompared to other pump types.

A further advantage is that the tube pump may be constructed to yield acompact yet robust and efficient pump.

Because of rod element of the pump element, the valve members will bepositioned in the tube at a predefined distance apart given by and fixedby the rod element whereby the amount of pumping may be equally welldefined for each deformation of the tube and possible to determine onbeforehand.

Furthermore, by the rod element being relatively stiff and inelasticcompared to the flexible tube portion, the rod element aids the tubeportion to relax and return to its undeformed shape after eachdeformation and each pumping movement. Hereby, the tube portion may beready for a new deformation and pumping cycle faster.

Further, the rod element enable a fast and simple assembly of the pumpelement and the tube pump as all the parts of the pump element may bymounted one after another on the rod element. The assembly mayadvantageously be performed from only one side which enables ahigh-speed and automated mass production.

Also, the rod element enables a fast yet precise and well-controlledinsertion of the pump element into the tube.

The rod element may further be provided with recesses for the differentparts of the pump element to be placed in. This facilitates the mountingand positioning of the parts on the rod element. Furthermore, thedistances between the parts and especially the distance between thevalve members and thereby the pumping volume may hereby be determinedand controlled accurately.

Also, the predetermined and fixed distance between the valve memberseases the mounting or placing of the tube pump in a pumping apparatussuch as an infusion pump.

The rod element may attain elongate shapes of different and/or varyingcross sections such as e.g. a circular cylindrical shape, a rectangularcylindrical shape, a hollow cylindrical shape, or a helical shape. Therod element may further comprise two or more parallel or non-parallelbars.

According to an embodiment of the invention, the pump element extendsinto the tube from one end of the tube, and the pump element furthercomprises at least one sealing part engaging with the tube wall in afluid tight fashion in one end of the tube. Hereby is obtained that thepumping element is easily inserted into a tube portion and that the pumpelement may also act as a coupling member for coupling the tube toanother part such as e.g a further tube, an infusion bag, a syringe orthe like without or with only minimal leaking. In this way the assembledtube pump may be made ready with only one connection or coupling.

The sealing part may engage with the tube wall by friction. The sealingpart may comprise one or more gaskets e.g. in the shape of a ring orband of rubber or another deformable or flexible material.

In a further embodiment of the invention, the pump element extendsthrough the entire length of the tube and comprises sealing partsengaging with the tube wall in a fluid tight fashion in both ends of thetube. Hereby a tube length of a predetermined length may bepre-manufactured and pre-assembled with the pump element alreadyinserted and secured to the tube wall. Hereby the sealing parts may bebrought to engage with the tube wall such as to be able to withstand ahigher fluid pressure e.g. by involving heat sealing or shrinking.

In a further embodiment of the invention, the tube is connected to afurther tube via a connection part. The connection part may beconfigured as a pipe connection part on the end of the pumping element.Hereby the tube pump may be easily fastened and secured to e.g. anothertube, an infusion bag, syringe or the like for pumping the fluid to orfrom such other part. This further yields the possibility to use lessexpensive tubes or hoses leading to or from the tube pump without beingconstrained by any tube diameter or tube material applied in the tubepump.

In yet a further embodiment of the invention, the tube pump comprises atleast one actuator of an electroactive polymer material arranged fordeforming the flexible tube portion when actuated. The electroactivepolymer material may be arranged on a wall portion of said flexible tubeportion and may hereby act to compress or enlarge the tube diameter whenactuated by the application of a current to the electroactive polymermaterial. The electroactive polymer material may for instance comprise asilicone and an electrically conductive layer.

In an embodiment of the invention the flexible tube portion may bysqueezed or compressed e.g. by the application of vacuum to the tube,prior to the electroactive polymer material being wrapped or otherwisearranged on the wall portion. When the vacuum is released and the tubepump is ready for use, the electroactive polymer material is therebyprestressed by the tube portion. A pretension of the electroactivepolymer material in the range of 10-50%, such as in the range of 20-30%may increase the efficiency of the electroactive polymer material. Asthe electroactive polymer material is subjected to a current, the lengthof the material film wrapped around the tube expands allowing for thetube diameter to increase creating a draw in the tube cavity. As thecurrent on the electroactive polymer material is released, the tubeportion is again compressed creating the pumping motion. More pump unitsmay be placed parallel or in series to increase the overall efficiencyof the pump.

The above described tube pump actuated by an electroactive polymermaterial may advantageously be driven by e.g. solar cells therebyobtaining a pump which may be manufactured at low costs and a reliablepump suitable for example outdoor pumping of water for e.g. the wateringof plants or animals, or for the oxidization of lakes or water holes bypumping water from the surface down to the bottom or vice versa. Thedisclosed tube pumps may work efficiently together with solar cells, inthat the tube pumps may work in a discontinuous manner whenever power isavailable with no need for large capacitors, but may yield at least asingle if not several pumping strokes with only minimal power.

In yet a further embodiment of the invention, the tube pump comprises atleast one actuator comprising a movable contact plate arranged fordeforming the flexible tube portion by compressing the tube whenactuated. The actuator may be linear or non-linear and may comprise oneor more contact plates placed to move towards each other and/or towardsa base, so that the tube may be compressed from one or more sides.

According to a further embodiment, the tube pump may comprise at leasttwo pump elements placed serially. By the use of a number of pumpingelements placed after each other, the pumping effect may be increasedequivalently by repeatingly deforming the tube in several positionsbetween sets of valve members. The tube may hereby be deformed in aperistaltic movement.

In an embodiment, at least one of the valve members comprises a flexiblediaphragm and/or membrane fitted onto the rod element and sized to atleast partly engage in its closed position with the inner wall of thetube. The pump element and thereby the tube pump may hereby beconstructed of very few parts in that the valve function is simplyobtained by the flexible membrane moving relative to the inner tubewall. Further, the valve members may be easily positioned onto the rodelement and may be easily exchanged if needed. The pump element andthereby the tube pump may hereby be manufactured at very low costs.

In a further embodiment of the tube pump according to any of the abovedescribed, the valve members comprise valves placed in valve housingswhich at least partly engage with the inner wall of the tube. Here, thevalve opening is primarily established in the valve housings, wherebythe valve opening is not dependent on the positioning within the tubeand therefore may be determined precisely beforehand and independent ofthe tube properties. Further, such construction may be more robust.

In a further embodiment of the tube pump according to any of the above,at least one of the valve members comprises a flexible funnel shapedmembrane and a perforated disk fitted onto the rod element, the diskbeing sized to engage with the interior of the tube in a fluid tightfashion. The membrane may be sized to cover the disk perforations ifpressed against the disk.

Hereby is established a very compact yet efficient non-return valvewhich may be configured to completely or partly close off any floweffectively in the one direction while allowing for a full flow in theother direction caused by a pressure difference across the valve. Thevalve may be opened by only a small pressure in dependence of thematerial properties and stiffness of the funnel shaped membrane. Thefunnel shaped (i.e. conical, cup shaped, or trumpet shaped) membraneincreases the efficiency of the valve and provides for a smoothcontinuous transition from its closed to its open position and viseversa without any ‘flapping’ or sudden changes of its shape. Hereby, amore even pumping motion without or with only minimal cudden changes inthe flow speed may be obtained.

In both the open and closed position of the valve, the disk liessealingly against the interior of the tube so that the only possiblefluid flow is through the perforations or openings in the disk. Thefunnel shaped membrane is mounted on the rod element only allowing forany possible fluid flow around the membrane in the space between themembrane and the tube walls. The membrane is oriented so that theinterior of funnel is oriented towards the disk. In the closed andrelaxed position of the valve, the membrane lies against the disk. Themembrane may lie completely or partly against the disk surface. Herebythe membrane covers at least some of the perforations in the diskpreventing the fluid flow therethrough. In the open configuration of thevalve, the membrane is deformed due to the increased pressure on thedisk side of the valve so that a gap is established between the disk andthe membrane allowing for a fluid flow through the perforations in thedisk and around the membrane.

The perforations in the disk may be applied as openings or holes throughthe disk placed randomly or in a pattern. The perforations may be placeda distance from the rod element or next to the rod element. Theperforations may e.g. be applied to the disk by the punching of a starshaped central hole in the disk both functioning as the hole for thedisk to be mounted on the rod element and providing the perforations forthe valve function.

The disk may be manufactured from e.g. a thermoplast, a metal, or arubber material.

The funnel shaped membrane may be punched or cut out from a foil, a filmor a cloth of e.g. a silicone material. The membrane may have a circularor oval shape with a central hole of a smaller diameter than thediameter of the rod element (optionally of the diameter of the recessedrod element) where the membrane is to be placed. As the membrane then ispushed or drawn onto the rod element, the initially flat membranenaturally attains a funnel shape and seals against the rod element.Alternatively, the membrane may be shaped e.g. by thermoshaping orthermoforming. In an embodiment of the invention the central part of thefunnel shaped membrane attains an angle in the range of 10-40 degreesrelative to the rod element. In a preferred embodiment the cone anglelies in the range of 20-35 degrees such as approximately 30 degrees.

Optionally, the funnel shaped membrane in the inlet valve may bemanufactured from a material of a lower stiffness than the membrane inthe outlet valve to ensure an easier an faster closing of the inletvalve thereby increasing the efficiency of the tube pump.

According to a further embodiment, the tube pump may comprise a freeflow prevention device mounted on the rod element between the first andsecond valve members, the free flow prevention device comprising a valveelement which in the closed configuration of the device is sized toengage with the interior of the tube in a fluid tight fashion, and whichis configured to be opened by the deformation of the flexible tubeportion pressing on at least a part of the valve element. The valveelement may simply comprise an element initially filling out theinterior of the tube but deforming differently from the tube, so thatopenings between the element and the tube may occur when the tube isdeformed e.g. as a part of the pumping, and such that the tube willagain be closed when the deformation of the tube seizes. The free flowprevention device may advantageously completely prevent any fluid flowwhen the tube is not deformed and pumping is not intended. Hereby, amore reliable and automatic closing of the tube may be achieved withoutthe need for any manual interaction such as the conventional manuallyplacing of clamps on the tube. The free flow prevention device furtheracts to make the open and closed configurations of the pump, and thephases of the pumping more distinct. The free flow prevention device mayfurther be used in a priming of the pump, i.e. in filling the pumpcavity between the valve members with fluid prior to initiating thepumping. This may be achieved by pressing (automatically or manually) onthe tube near the device opening the free flow prevention device.

The free flow prevention device according to embodiments of theinvention is furthermore advantageous in preventing the free flow whilestill allowing the pumping with only small pressure forces on the tube.The stiffness of the free flow prevention device may be tailored torequire a desired minimum deformation of the tube or minimum deformationforce on the tube to enable any fluid flow.

The valve element of the free flow prevention device may comprise afunnel-shaped membrane of a larger diameter than the interior diameterof the tube, thereby sealing off the tube when not compressed. Thefunnel shaped membrane may be manufactured from a flat cloth in the sameway as described in relation to the funnel shaped membranes of the valvemembers. Advantages of a funnel shaped membrane are as described inrelation to the funnel shaped membranes of the valve members.

The valve element of the free flow prevention device may comprise a foammember preferably of a foam with closed cells and e.g. of a cubic shape.The foam member is easily deformed with minimal forces and may bemanufactured and assembled efficiently and at low costs.

The prevention of any free flow in the tube pump is especially importantin relation to applications of the tube pump in infusion pumps, wherethe unintended free flow of medicine is estimated to have added to orbeen the direct cause of death of about 500 persons in the USA.

According to another aspect, the invention relates to a pump element fora tube pump as described above, where the pump element is configured forinsertion into a tube and to aid in generating a flow of a fluid withinthe tube. The pump element comprises a rod element with at least a firstand a second non-return valve members positioned a distance apart on therod element and oriented in the same direction relative to the rodelement so as to allow for a fluid flow through the first valve member,along the rod element, and through the second valve member. Hereby thepump element when inserted in a flexible tube may act to generate afluid flow through the tube upon repeated deformation of said tubebetween said first and second valve members. It should be understoodthat the invention in this aspect may relate to a pump element as anisolated product independent of the tube pump for which it is intendedto be used.

A pump element according to the above is advantageous for the samereasons as apply to the tube pump given in the previous.

The pump element is advantageous in comprising only few parts and whichmay be easily assembled. Also the pump element is inexpensive tomanufacture and therefore advantageous as a disposable product, whichmay be advantageous for medical applications or in the food industrywhere hygiene or sterile equipments are of outmost importance.

The pump element is further advantageous in being easy and fast toinsert in a tube whereby a tube pump may be made ready for operationfast and easily.

Further, because of the pump element construction, the valve memberswill inevitably be inserted in a tube at the predefined distance apartas given by their position on the rod element, whereby the amount ofpumping may be equally well defined for a given deformation of the tube.

In an embodiment of the invention, the pump element further comprises asealing part positioned on one side of the first and second valvemembers and configured to establish a fluid tight connection to an endpart of a tube when the pump element is inserted in the tube.

Further, the pump element may comprises a pipe connection partconfigured for connecting the pump element to a further tube, syringe,infusion bag or the like. Hereby is obtained that a tube in which apumping motion is generated is easily connected and coupled to anotherpart via the pump element such that fluid may be pumped on to this otherpart. In this way a minimum of couplings are needed and the risk ofleaks is minimized.

In a further embodiment, the first and second valve members comprisevalves belonging to the group of ball valves, duckbill valves, diaphragmvalves, wafer valves, check valves, swing check valves, disc checkvalves, split disc check valves, tilting disk check valves, cross slitvalves, umbrella valves, and lift-check valves. Hereby may be obtained aset of effective valves and which may be pre-manufactured and positionedin the valve members in a simple yet effective manner.

In an embodiment of the invention, the valve members used in one pumpelement may of different types. For instance, the inlet valve may berelatively soft compared to the outlet valve whereby a larger pressureis needed to open the outlet valve thereby minimizing or avoiding anyfree flow in the tube. This may be especially advantageous for pumpsinvolving dosing of medicine where it is important to know the exactflow through the pump to ensure the correct dosage.

In a further embodiment of the invention, the connecting rod is made ofa bendable material such as a thermoplast (other material types?).Hereby is obtained that the pump element may be easily inserted intobended tubes or hoses or that the tube may be bended without affectingthe efficiency of the pumping. Further, a more compact tube pump may beobtained by allowing the tube to bend.

In a further embodiment of the invention, the connecting rod is made ofa plastic material such as e.g. PE (polyethylene), PP (polypropylene), arubber, or a metal alloy.

The invention further relates to an infusion pump comprising a tube pumpaccording to any of the embodiments described in the preceding. Theadvantages hereof are as given in relation to the tube pump. Further,the infusion pump is advantageous in making the use of a drip counterand a flow regulator superfluous, as otherwise conventionally applied ininfusion pumps, as the tube pump can be controlled and regulated to givea certain number of pulses per time whereby the flow may be accuratelydetermined. Further, the infusion pump can maintain a constant flowratethroughout the entire emptying of the infusion bag and regardless of howthe infusion bag is placed. In contrast hereto conventional infusionpumps uses the gravity for a continued and complete emptying of theinfusion bag for which reason it may be essential that the infusion bagand the tube leading from the infusion bag must hang or be heldcorrectly.

In a further aspect, the invention relates to a non-return valve memberfor use in a tube pump as described above, where the valve member isconfigured for insertion into a tube and to aid in controlling a flow ofa fluid within the tube. The valve member comprises a flexible funnelshaped membrane, and a perforated disk sized to engage with the interiorof the tube in a fluid tight fashion. The valve member further comprisesa rod element onto which the disk and the membrane are mounted.

In an embodiment of the invention, the funnel shaped membrane in theclosed configuration of the valve member is placed such as to cover thedisk perforations.

In a further embodiment of the invention, the membrane is mounted on therod element by sticking the rod element through a hole in the membrane,the hole being of a smaller diameter than the diameter of the rod.

The advantages of such non-return valve as described above are as givenin relation to the tube pump comprising such valve member.

In a final aspect, the invention relates to a method for creating a flowof a fluid within an at least partly flexible tube, comprising the stepsof connecting at least a first and a second non-return valve member to aconnecting rod element a distance apart and such that said first andsecond valve members are oriented in the same direction relative to therod element, and inserting the rod element with the valve members intothe tube such that said valve members when closed at least partly engagewith the tube wall. The method further comprises repeatingly deformingat least a part of the tube between the first and second valve membersthereby alternately closing and opening the valve members and therebygenerating a fluid flow through the tube.

The advantages hereof are as given in relation to the tube pump and thepump element in the previous paragraphs.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following different embodiments of the invention will bedescribed with reference to the drawings, wherein:

FIG. 1 illustrates an embodiment of a tube pump with a pump elementinserted in a tube as seen in a cross sectional views from the side,

FIG. 2 illustrates the tube pump as shown in FIG. 1 in a perspectiveview,

FIGS. 3A and 3B illustrate the working principle of a tube pumpaccording to the invention during and after deformation of the tube byan external compression force,

FIGS. 4A and 4B illustrates the working principle of a tube pumpaccording to the invention during and after deformation of the tube byan electroactive polymer material,

FIGS. 5 and 6 illustrate different embodiments of a tube pump and a pumpelement with a electroactive polymer material,

FIGS. 7-11 illustrate different embodiments of a tube pump and a pumpelement with different types of valve members,

FIG. 12 illustrates an embodiment of a tube pump with a number ofpumping elements in a serial connection, and the coupling of two tubeparts by means of a pump element,

FIG. 13 illustrates an infusion pump comprising a tube pump and a pumpelement according to embodiments of the invention,

FIGS. 14 and 15 illustrates a further embodiment of a tube pump and apump element with a free flow prevention device according to theinvention,

FIG. 15 illustrates a further embodiment of a tube pump and a pumpelement with an electroactive polymer material,

FIGS. 17A and B illustrate different embodiments of a tube wall in across sectional view suitable for considerable deformations, and

FIGS. 18A, B, and C illustrate the working principle of a furtherembodiment of a tube pump and a pump element with a different type of afree flow prevention device.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embodiment of a tube pump, 100 according to theinvention and as seen in a cross sectional view. The same tube pump isseen in a perspective view in FIG. 2. The tube pump 100 comprises a tube101 (in grey) into which is inserted a pump element 102. The pumpelement 102 is also depicted in FIG. 2 below in a perspective view asseen before insertion into the tube. The pump element 102 comprises twoor more non-return valve members 103 attached to a rod element 104 in aspaced apart manner. The two valve members are oriented in the samedirection relative to the rod element 104, so that a fluid inside thetube portion 101 may only flow in one direction through the two valvemembers 103 as illustrated by the arrow 105. The valve members 103 herecomprises split disc or duo check valves comprising a split disk whichis dimensioned to have a larger surface area than the tube crosssectional area so that the disks only allow for a fluid flow in the onedirection. The rod element 104 here is in the shape of a flat bar foroptimally supporting the split disk valves but could also have othershapes such as circular. Other possible shapes are shown in some of thefollowing figures. The pump element 102 further comprises a connectingpart 106 at its end for connecting to another tube or hose 107. Theconnection part 106 could equally well be dimensioned and shaped toconnect to tubes of smaller or larger diameters, to e.g. a syringe, or ainfusion bag or the like. The pump element further comprises a sealingpart 108 establishing a fluid tight connection between the pump elementand the tube 101 when the pump element is inserted herein. The sealingpart may optionally comprise one or more gaskets (not shown).

FIGS. 3A and 3B illustrate the working principle of the tube pump 101 ingeneral. The tube 101 surrounding the pump element 102 comprises aflexible tube wall portion 301 positioned between the two valve members103. The pumping is generated by deforming the tube between the valvemembers 103, which in this illustrated example is performed by anactuator compressing the tube 101 by means of two movable contact plates302, the first valve member 103 a will remain closed due to theincreased pressure in the tube, whereas the second valve member 103 bwill be opened. Thereby the fluid is forced in the direction of thearrow 303. As the contact plates 302 retract (as shown in FIG. 3B) andthe tube deformation is relaxed, an under pressure is created in thedecompressed chamber between the valve members causing the second valvemember 103 b to close and the first valve member 103 a to open and aflow in the direction of the arrow 304. A fluid flow in the tube isthereby obtained by a repeating deformation of the tube between thevalve members 103.

FIGS. 4A and 4B illustrates the same pumping principle, but where thedeformation of the tube 101 is effected by an electroactive polymermaterial 400 which changes its size considerably when subjected to acurrent. In this tube pump embodiment the electroactive polymer material400 is placed in or on a part of the flexible tube wall thereby actingto compress the tube when actuated.

In FIG. 5 is shown another embodiment of a pump element 102 configuredfor insertion into a tube 101. The tube 101 in this case comprises twobands 501 of an electroactive polymer material which when activated mayact to compress the tube 101 in two places. The pump element 102 in thisembodiment comprises three valve members 103 which each comprises a diskcheck valve 502 in a valve housing 503. The valve housings 503 aredimensioned to fit inside the tube 101 on either side of each band 501of electractive polymer material. Both sealing parts 108 in each end ofthe pump element 102 are hollow or perforated allowing the fluid to flowpast the sealing parts inside the tube. The bands of electroactivepolymer material may be activated on after the other in serial therebygenerating a peristaltic pumping motion.

FIGS. 6A and 6B likewise illustrate the use of electroactive polymermaterial in the actuator deforming the tube 101 in a tube pump 100according to the invention. Here, the electroactive polymer material isplaced in broader ribbons or bands 601 in a hinged frame 502. FIG. 6Ashows the actuator bands 601 in their relaxed state where the frameparts 602 lay up against the tube wall. In FIG. 6B can be seen how theelectroactive polymer bands 601 contract when electrically activated (asindicated by the hatched lines) thereby forcing the frame parts 602 tocompress or squeeze the tube 101.

Different types of non-return valve members may be applied in the pumpelement 102 as illustrated in the FIGS. 7-11. These figures alsoillustrate different possible shapes of the rod element 104 and of thepipe connection or coupling part 106.

The pump element 102 as shown in FIG. 7 comprises valve members 103 inthe shape of flexible diaphragms or membranes 701 fitted onto the rodelement and sized to at least partly engage in their closed positionwith the inner wall of the tube 100. The pump element alone is shown inFIG. 7A, as inserted in a tube and in a tube pump in FIGS. 7B and 7C ina side view and perspective view, respectively.

The pump element 101 may additionally or alternatively comprise valvesof the disk check type 801 (FIGS. 8A and 8B), valves of a soft orelastic material such as a silicone, rubber or thermoplastic materialand with a movable lid providing for the valve opening 901 (FIG. 9),duckbill valves 1001 (FIGS. 10A and B), or ball valves 1101 (FIG. 11).

FIG. 12 illustrates an embodiment of a tube pump 100 with a number ofpump elements 102 placed in one or more tubes 101 in a serial. Herebythe pumping effect may be correspondingly increased, in that the tube ortubes 101 may be compressed in more than one place. This mayadvantageously be done one place after each other thereby establishing aperistaltic movement. The figure further illustrates how two or moretube parts 101 may be coupled to each other and brought in fluidconnection by means of the one or more pump elements 102.

FIG. 13 illustrates an infusion pump 1301 comprising a tube pump 100 anda pump element 102 according to embodiments of the invention. Here, thepump element 101 is inserted in a tube, coupling the tube to a furthertube or hose at each end of the pump element which may be coupled at oneend to a syringe 1302 and at the other to an infusion bag of bottle (notshown). The infusion pump using a tube pump according to the inventionis advantageous over conventional infusion pumps by being able toprovide a well-controlled and steady flow irrespective of theorientation of the pump (independent of the gravity force) andirrespective of the amount of fluid left in the infusion container.Rather the infusion speed and amount can be precisely controlled andregulated by controlling the actuator force of the one or more actuatorsdeforming the flexible tube, 1303.

The tube pump according to the various embodiments may likewiseadvantageously be applied in other types of pumps such as pumps drivenby solar cells for instance in pumps for increased oxidisation of waterwhere water from lower regions of for instance a lake or water basin israised and pumped to higher regions thereby mixing the water. Thedisclosed tube pumps may work efficiently together with solar cells inthat the tube pumps may work in a discontinuous manner whenever power isavailable, and may yield at least a single if not several pumpingstrokes with only minimal power.

FIG. 14 discloses an embodiment of a pump element 102 inserted into aflexible tube thereby forming a tube pump 100. The figure shows thedifferent parts of the pump elements as assembled and in an explodedview, respectively. In this embodiment the two non-return valve members103 each comprise a funnel-shaped flexible membrane 1401 of a smallerdiameter than the interior diameter of the tube 101. These membranes mayinitially be flat membranes of circular shape provided with a centralhole of smaller dimension than the diameter of the rod element. Themembranes may as an example be punched out or cut from films or foils ofa flexible material such as silicone.

When pushed onto the rod element, the membrane deform into a funnel asillustrated in the figure. The funnel shaped membranes are each placedon the rod element 104 next to a disk 1402 of an outer dimension andshape so as to lie and seal against the interior of the tube. The disks1402 comprise a number of openings 1403 which may be placed next to therod element as illustrated on one of the valve members 1405 or as apattern on the disk 1406. When the non-return valve member is closed asillustrated in the topmost configuration in FIG. 14, the funnel shapedmembrane 1401 lies against at least the outer part of the neighbouringdisk 1402. In case of a larger fluid pressure to the disk side of thevalve (to the left in the figure) than to the membrane side (to theright in the figure), the membrane will be pushed away from the diskallowing for a fluid flow through the openings of the disk and aroundthe membrane as sketched by the arrows 1407. An increased fluid pressureon the membrane side of the valve member, however, will cause themembrane to press more tightly against the disk preventing any fluidflow. The rod element 104 may optionally be provided with recesses forreceiving and positioning the different parts of the pump elementwhereby the distance between the non-return valve members and therebythe pumping volume can be determined and controlled accurately.

The pump element illustrated in FIG. 14 further comprises a free flowprevention device 1410 which is a valve element configured such that itonly opens and allows for passage of a fluid when affected by a pressurefrom the exterior on the tube. Hereby any unintentional fluid flowthrough the pump may be prevented which may otherwise be the probleme.g. for hanging infusion pumps where the gravity forces from a bags ofinfusion fluids may cause a small unnoticeable leak in the infusionpump. In the illustrated embodiment the free flow prevention device issimply made of a circular membrane placed on the rod element 104somewhere between the two valve members 103 and of an outer diameterlarger that the interior diameter of the tube 101. Like for themembranes 1401 in the valve members 103, the membrane of the free flowprevention device is given a funnel shape by being pushed on the rodelement through a hole of a smaller dimension than the diameter of therod element. As a pressure is applied to the tube, the tube deformsdifferently than the free flow prevention device making openings betweenthe device and the tube wall for the fluid to flow through. When thepressure is released, the free flow prevention device attains itsundeformed shape and closes off any flow through the tube again.

Further, the free flow prevention device may advantageously be used toprime the tube pump, i.e. fill the tube cavity between the non-returnvalve members with fluid prior to initiating any pumping. This may beperformed by simply pressing manually or automatically on the tube nearthe free flow prevention device,

FIG. 15 shows a tube pump 100 and a pump element 102 similar to the pumpelement described in relation to FIG. 14. Only here, the tube pump isconfigured to be attached to other tubes or hoses via the connectionparts 106 in each end of the pump element and placed on each end of therod element 104. Further, in this embodiment the first perforated disk1501 (the openings in the disk not shown in the figure) sealing of theone end of the tube 101 and the connection part 106 is manufactured inone piece. The tube pump may in this way be manufactured from a minimalnumber of parts which furthermore may be effectively and fast assembledin a production line from optionally just one side.

FIG. 16 depicts an embodiment of a tube pump suitable to be actuated bymeans of an electroactive polymer material 400. Here, an intermediatemember 1600 is applied on a part of the rod element 104 between thefirst and second non-return valve members 103. After assembling thedifferent parts of the pump element and placing the pump element insidethe tube 101, the tube may be shrinked or squeezed onto or close to theintermediate member 1600 by the application of vacuum to the pumpelement and the electroactive polymer material (not shown) is wrappedtightly around the compressed tube and the vacuum is released. As theelectroactive polymer material is actuated, the material expands therebyallowing the tube of the tube pump wrapped by the material to expandlikewise and vice versa. In the shown embodiment of the pump element,the non-return valve members comprise flexible membranes and perforateddisks like in the embodiment described in relation to the FIGS. 14 and15. The type of the non-return valves used is however not of importancein relation to the described use of the electroactive polymer material,and other types of non-return valves may therefore likewise be appliedin relation to the depicted tube pump of FIG. 16. In this embodiment,the connection parts 106 are configured to receive and connect to tubesor hoses through interior passageways.

In order to allow for the compression of the tube against theintermediate member 1600 the tube may for instance be made of a materialcomprising closed pores 1700 as illustrated in FIG. 17A. Alternatively,the tube may have a tube wall comprising grooves or channels 1701 assketched in FIG. 17B whereby the tube diameter may be decreasedconsiderably during the tube compression with minimal wear and fatigueon the tube.

FIG. 18 shows sketches of another embodiment of a free flow preventiondevice 1410 according to the invention. Here, the free flow preventiondevice is shaped as a hatch-like member 1800 in connection to one of thenon-return valve members 103 and likewise placed on the rod element (notshown). In the neutral position of the tube pump as shown in FIG. 18A,the flow is prevented in both directions of the tube. In the pumpingphase illustrated in FIG. 18B, a compression and a deformation of thetube 101 causes the free flow prevention device to open as the tube wallpresses against the hatch-like member 1800. The outlet valve 1802 isfurther opened and the inlet valve 1803 closed by the increased fluidpressure. As the external pressure is removed tube from thin the lastphase (FIG. 18C) the outlet valve 1802 is closed and the inlet valve1803 is opened by the lower pressure in the tube cavity between thevalves. Furthermore, the free flow prevention device closes due to therelaxation of the tube. The described free flow device may likewise beapplied in combination with other types of non-return valves than theones illustrated here.

While preferred embodiments of the invention have been described, itshould be understood that the invention is not so limited andmodifications may be made without departing from the invention. Thescope of the invention is defined by the appended claims, and alldevices that come within the meaning of the claims, either literally orby equivalence, are intended to be embraced therein.

1. A tube pump comprising a tube and a pump element inserted in saidtube, the pump element comprising a rod element and at least a first anda second non-return valve member positioned a distance apart on said rodelement and oriented in a same direction relative to the rod element soas to allow for a fluid flow in the tube through the first valve member,along the rod element, and through the second valve member, and the tubecomprising an at least partly flexible tube portion between said firstand second valve members such that a repeated deformation of saidflexible tube portion acts to alternately close and open the valvemembers thereby generating a fluid flow through the tube.
 2. The tubepump according to claim 1, where the pump element extends into the tubefrom one end of the tube, and where the pump element further comprisesat least one sealing part engaging with the tube wall in a fluid tightfashion in one end of the tube.
 3. The tube pump according to claim 1,where the pump element extends through the entire length of the tube andcomprises sealing parts engaging with the tube wall in a fluid tightfashion in both ends of the tube.
 4. The tube pump according to claim 1,where the tube is connected to a further tube via a connection part. 5.The tube pump according to claim 1 comprising at least one actuator ofan electroactive polymer material arranged for deforming said flexibletube portion when actuated.
 6. The tube pump according to claim 5, wheresaid electroactive polymer material is arranged on a wall portion ofsaid flexible tube portion.
 7. The tube pump according to claim 1comprising at least one actuator comprising a movable contact platearranged for deforming said flexible tube portion by compressing thetube when actuated.
 8. The tube pump according to claim 1 comprising atleast two pump elements placed serially.
 9. The tube pump according toclaim 1, where at least one of the valve members comprises a flexiblemembrane fitted onto the rod element and sized to at least partly engagein its closed position with the inner wall of the tube.
 10. The tubepump according to claim 1, where the valve members comprise valvesplaced in valve housings at least partly engaging with the inner wall ofthe tube.
 11. The tube pump according to claim 1, where at least one ofthe valve members comprises a flexible funnel shaped membrane and aperforated disk fitted onto the rod element, the disk being sized toengage with the interior of the tube in a fluid tight fashion.
 12. Thetube pump according to claim 11, where the membrane is sized to coverthe disk perforations if pressed against the disk.
 13. The tube pumpaccording to claim 1, further comprising a free flow prevention devicemounted on said rod element between said first and second valve members,the free flow prevention device comprising a valve element which in theclosed configuration of the device is sized to engage with the interiorof the tube in a fluid tight fashion, and which is configured to beopened by said deformation of said flexible tube portion pressing on atleast a part of said valve element.
 14. The tube pump according to claim13, where the valve element of the free flow prevention device comprisesa funnel-shaped membrane.
 15. The tube pump according to claim 13, wherethe valve element of the free flow prevention device comprises a foammember.
 16. A pump element for a tube pump according to claim 1, wherethe pump element is configured for insertion into a tube and to aid ingenerating a flow of a fluid within the tube, the pump elementcomprising said rod element with at least said first and secondnon-return valve members positioned a distance apart on said rod elementand oriented in the same direction relative to the rod element so as toallow for a fluid flow through the first valve member, along the rodelement, and through said second valve member, whereby the pump elementwhen inserted in a flexible tube may act to generate a fluid flowthrough said tube upon repeated deformation of said tube between saidfirst and second valve members.
 17. The pump element according to claim16, where the pump element further comprises a sealing part positionedon one side of said first and second valve members and configured toestablish a fluid tight connection to an end part of a tube when thepump element is inserted in said tube.
 18. The pump element according toclaim 16, where the pump element further comprises a pipe connectionpart configured for connecting the pump element to a further tube. 19.The pump element according to claim 16, where said first and secondvalve members comprise valves belonging to the group of ball valves,duckbill valves, diaphragm valves, wafer valves, check valves, swingcheck valves, disc check valves, split disc check valves, tilting diskcheck valves, cross slit valves, umbrella valves, and lift-check valves.20. The pump element according to claim 16, where the connecting rod ismade of a bendable material such as a thermoplast.
 21. The pump elementaccording to claim 16, where the connecting rod is made of PE(polyethylene), PP (polypropylene), a rubber, or a metal alloy.
 22. Theinfusion pump comprising a tube pump according to claim
 1. 23. A methodfor creating a flow of a fluid within an at least partly flexible tube,comprising the steps of connecting at least a first and a secondnon-return valve member to a connecting rod element a distance apart andsuch that said first and second valve members are oriented in a samedirection relative to the rod element, inserting said rod element withsaid valve members into said tube such that said valve members whenclosed at least partly engage with the tube wall, repeatingly deformingat least a part of the tube between said first and second valve membersthereby alternately closing and opening said valve members and therebygenerating a fluid flow through the tube.
 24. The non-return valvemember for use in a tube pump according to claim 1, where the valvemember is configured for insertion into a tube and to aid in controllinga flow of a fluid within the tube, the valve member comprising aflexible funnel shaped membrane and a perforated disk sized to engagewith the interior of the tube in a fluid tight fashion, the valve memberfurther comprising a rod element onto which the disk and the membraneare mounted.
 25. The valve member according to claim 24 where the funnelshaped membrane in the closed configuration of the valve member isplaced such as to cover the disk perforations.
 26. The valve memberaccording to claim 24 where the membrane is mounted on the rod elementby sticking the rod element through a hole in the membrane, the holebeing of a smaller diameter than the diameter of the rod.